What does the excess flow in a liquid service valve do?

The function of an excess flow liquid service valve is critical for safety in fluid handling systems. The correct answer accurately describes that the valve closes when the outward flow of gas exceeds a predetermined safe rate. This is essential for preventing hazardous situations that could arise from excessive flow, such as leaks or pressure build-up.

By automatically shutting off flow when it detects conditions beyond safe operational limits, the excess flow valve acts as a protective measure, ensuring that the system can maintain safe operating parameters and prevent potential accidents. This is particularly important in applications where the integrity of the containment system is vital for safety and environmental protection.

The focus on safety and compliance with standards underlines the importance of having such a valve in liquid service applications. Other options do not accurately describe the essential safety feature provided by the excess flow valve.